Gene Fuller wrote:
Is there some mystery here? The explanation is very straightforward. No
need for ... counter-balanced construction and destruction, ...

On the contrary, energy cannot be created or destroyed.
The "missing energy" from the destructive interference
at the standard output appears as constructive
interference at the non-standard output. Your assertion
above violates the conservation of energy principle.

Suppose that the "standard output" is at a constructive maximum.

Contrary to what you say above, that cannot happen without
destructive interference occurring somewhere else. That
constructive maximum is going to exhibit more joules/sec
than the laser beam source. Where does the extra energy
come from?
--
73, Cecil http://www.w5dxp.com